1. Field of the Invention PA1 2. Description of Related Art
The present invention relates to a feed screw mechanism in which a rotation of a lead screw is converted in to a linear movement.
In an application of such a feed screw mechanism, for example, to a camera, the lead screw is engaged by a pin which is connected to a lens groups of the camera, so that the rotation of the lead screw causes the lens groups to move in the optical axis direction thereof to carry out a predetermined operation, such as zooming, etc.
In such a known feed screw mechanism, if the lead screw fails to correctly engage with the pin, a possible oscillation or shock applied to the camera causes the pin to skip over the correct tooth of the lead screw to be engaged, thus resulting in an error in the engagement. This makes it impossible to move the lens groups by the correct distance in the optical axis direction.
Moreover, if a camera in which the feed screw mechanism is incorporated is provided with a pair of lens groups which are driven by the respective lead screws, it is necessary to provide a pair of separate lens driving mechanisms including lead screws. This not only increases the number of camera components, but also complicates the camera design in view of a difficulty in matching components.